Chapada Diamantina Mountains Research Articles

<I>Spirotheca elegans</I> (Malvaceae: Bombacoideae), a New Species from Bahia, Brazil

Abstract Spirotheca elegans , a new species of Malvaceae subfamily Bombacoideae from the state of Bahia, Brazil, is described and illustrated. It is considered to be endemic to an area of Caatinga vegetation bordering the Chapada Diamantina mountain range, in the central region of the state. Notes on its distribution, ecology, phenology, and comments on its conservation status are given. Furthermore, a discussion of the relationship of the new taxon to other species of Spirotheca and an updated key are provided.

Pollination ofCambessedesia wurdackiiin Brazilian Campo Rupestre Vegetation, with Special Reference to Crepuscular Bees

Cambessedesia wurdackii Martins (Myrtales: Melastomataceae) is presumably endemic to the Chapada Diamantina, Bahia State, Brazil. A majority of the species of this family are pollinated by diurnal bees that buzz the floral anthers to collect pollen. The present work examined the interactions between C. wurdackii and visiting bees, focusing on temporal, morphological, and behavioral features, especially in regards to the crepuscular bees Megalopta sodalis (Vachal) (Hymenoptera: Halictidae) and Ptiloglossa off. dubia Moure (Hymenoptera: Colletidae). The study was undertaken in an area of campo rupestre montane savanna vegetation located in the Chapada Diamantina Mountains of Bahia State, Brazil, between August/2007 and July/2008. Flowering in C. wurdackii occurred from April through July, with a peak in May. A total of 592 visits by diurnal and crepuscular bees to the flowers of C. wurdackii were recorded, with a majority of the visits made by M. sodalis and P. dubia (92%) near sunrise and sunset. The anthers of C. wurdackii are arranged in two tiers, which favors cross pollination. The morphological, temporal and behavioral characteristics of M. sodalis and P. dubia indicated that they were potential pollinators of C. wurdackii, in spite of the fact that the colorful and showy flowers of this species are more typical of a diurnal melittophilous pollination syndrome.

Leaf phenology and water potential of five arboreal species in gallery and montane forests in the Chapada Diamantina; Bahia; Brazil

The influence of water potential ( Ψ W) on the leaf phenological behaviors of five arboreal species within gallery and montane forests on the eastern slope of the Chapada Diamantina Mountain Range in Bahia State, NE Brazil, was examined to investigate the following questions: (1) Do seasonal variations in rainfall influence the water potential of these species in their natural habitats (gallery and montane forests)? (2) Do the gallery forest species show smaller daily variations in their water potential and greater nocturnal recuperation than montane species? (3) Can the water potentials of these species be used to identify their particular types of leaf phenologies? The species examined were Tibouchina fissinervia and Clusia nemorosa (evergreen with continual leafdrop); Tapirira guianensis and Vochysia pyramidalis (evergreen with concentrated leafdrop), and Maprounea guianensis (brevi-deciduous) were chosen based on their abundance, importance value indices, and contrasting phenological behaviors. The leaf phenologies of all species were similar in both forest types. Evergreen species with continual leafdrop demonstrated leaf budding and leaf fall occurred at low levels during the entire year. Evergreen species with continual leafdrop as well as brevi-deciduous species demonstrated peaks of leaf fall and leaf budding during the dry period. Brevi-deciduous trees remained without leaves for an average of three days. The major episodes of leaf budding occurred during the dry period in all of the species examined. M. guianensis usually demonstrated low predawn ( Ψ PD) and midday ( Ψ MD) water potentials ( Ψ W). C. nemorosa demonstrated the greatest Ψ PD and Ψ MD values and the lowest daily amplitude ( Δ Ψ ), suggesting that this plant used CAM during most of the study period. The majority of the species demonstrated small seasonal differences in Ψ W, and the Ψ PD values indicated a satisfactory nocturnal recuperation of their water status, even during the dry period. The maximum daily amplitude of Ψ W was observed in V. pyramidalis, a species dependent on moist habitats for establishment and growth. No large decrease in Ψ PD was observed during the study period in the species examined here, and all species demonstrated leaf budding during the dry period, suggesting that there were no severe water restrictions in either the gallery or montane forests. However, during dry periods, the species generally demonstrated lower Δ Ψ . This reflects the restriction of transpiration, which according to phenological data, may occur due to different mechanisms, depending on the species. Our data supports the view that there is no strict relationship between decreasing water status in these plants and leaf fall.

Phenology of Gallery and Montane Forest in the Chapada Diamantina, Bahia, Brazil1

Abstract Phenological studies were carried out in gallery and montane forests along the Lencois River in the Chapada Diamantina mountains, state of Bahia, Brazil, between January 1993 and March 1998. Leaf flush, leaf fall, flowering, and fruiting were followed in 54 tree species (N = 243 trees tagged along trails following the river margin and the valley sides). Both gallery and montane forests exhibited a moderate peak in leaf fall during the dry season (August–October), as well as increased leaf flushing in the rainy season (December–April). Three basic modes of leafing activity were noted, although most trees in the gallery forest and in the montane forest were evergreen (82.3 and 57.8% relative frequency, respectively). In both forest types, flowering and fruiting modes were annual, with peaks of activity during the rainy season. The predominantly evergreen mode of leaf fall and leaf flush found in this study was most similar to that seen in tropical wet forests, while the flowering and fruiting modes...